1. Field of the Invention
The present invention is directed to an apparatus for compensating for the weight of a supported object, such as for compensating for the weight of an x-ray radiator in a sealing-mounted medical device.
2. Description of the Prior Art
German Utility Model GM 87 06 358 teaches a weight compensating apparatus, particularly for a medical device, wherein a cable drum is provided for accepting at least one cable capable of carrying a weight such as an x-ray radiator, the cable drum being loadable by the force of a spiral spring element, and wherein a safety arrangement is provided for triggering a signal given a cable breakage. An electromagnetically actuatable friction brake is provided at the weight compensating apparatus which acts on the cable drum, or its cover, in order to be able to stop rotation thereof when the x-radiator, which is height-adjustable at a ceiling stand, is to be held in place in arbitrary vertical positions.
In this weight compensating apparatus a spring breakage could allow an unintentional displacement of the weight, i.e. the x-radiator, due to gravity as a result of the reduced counterforce caused by the breakage.
A break in the outer region of the spiral spring is particularly problematic, because this results in this outer region of the spiral spring braces itself at the spring drum, the counterforce essentially applied by the spiral spring then depending solely on the friction at the housing. As a result of such a spring breakage, the weight is slowly displaced according to the force of gravity. Safety means which act in the manner of a safety belt given a breakage of the inner region of the spiral spring could not respond to a breakage of the outer region of the spiral spring due to the abrupt cancellation of the counterforce emanating from the spiral spring.